Creating an Elementor Plugin: I’ve copied the PHP example code, but how do I enable it?

I’m not very experienced with PHP, so please bear me. I’ve copied and pasted the example code from the official documentation into my plugin subfolder and – as I expected – the example is not complete. the piece of code is not executed. As far as I know in fact, PHP is not executing a class if I don’t call it explicitly.

I could simply instantiate an object of my widget class, but is that the correct way? Which is the standard way to execute the PHP code that loads an Elementor Widget?

I see there is a module.php file in each widget subfolder containting some code like this: